Strongly Secure Authenticated Key Exchange Protocol Based on Computational Diffie-Hellman Problem

Currently, there are a lot of authenticated key exchange (AKE) protocols in literature. However, the security proofs of this kind of protocols have been established to be a non-trivial task. The main issue is that without static private key it is difficult for simulator to fully support the SessionKeyReveal and EphemeralKeyReveal queries. Some proposals which have been proven secure either just hold in relatively weak models which do not fully support above-mentioned two queries or make use of the stronger gap assumption. In this paper, using a new technique named twin Diffie-Hellman problem proposed by Cash, Kiltz and Shoup, we present a new AKE protocol based on the computational Diffie-Hellman (CDH) assumption, which is more standard than gap Diffie-Hellman (GDH) assumption. Moreover, our scheme is shown to be secure in strong security definition, the enhanced Canetti-Krawczyk (eCK) model introduced by LaMacchia, Lauter and Mityagin, which better supports the adversaries’ queries than previous models.